Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
A user that uses drawing software such as a computer aided design (CAD) software frequently sets a background color to black or dark grey for preventing eyestrain or similar reason when the user draws a color line image.
When this color line image is printed, the background color is changed into white or transparent for reduction of the toner amount and/or due to the optical characteristics of an output paper. However, a consequent problem is that this makes it difficult to see a line-drawing color of a part of a line-drawing object.
For example, in the case where the line-drawing color is yellow, the visibility is good with the background color of black during drawing. On the other hand, the visibility is poor with the background color of white on a paper sheet after printing. In particular, when printed with a black-and-white printer or similar printer, the line-drawing color of white or yellow is converted into black and white so as to be a light black line. This light black line is hardly visible depending on the gamma characteristic and the screen characteristics. Alternatively, jaggy might become eye-catching.
In response, to improve the visibility of the line-drawing object with the line-drawing color of yellow, there is a technique that employs a high-resolution screen only in the problematic part so as to reduce the jaggy.
However, with this technique, the color of the line-drawing object itself is still light. This technique cannot ensure sufficient visibility.
Accordingly, for example, the user of CAD or similar tool changes the white line-drawing color of the line-drawing object into black and changes the yellow line-drawing color of the line-drawing object into orange for printing manually, so as to ensure visibility of the black-and-white printing.